Object detection system and article display shelf

ABSTRACT

Provided is an object detection system including: a ranging device that emits light so as to pass through a detection region and receives reflected light in which the ranging device is configured to perform a scan by changing an optical path of emitted light; and a reflection member that is provided in a scan range so as to reflect light passing through the detection region toward the ranging device.

TECHNICAL FIELD

The present invention relates to an object detection system and a sensor device.

BACKGROUND ART

Patent Literature 1 discloses a vehicle measuring apparatus that measures the size of a vehicle by irradiating a light beam toward a road surface. Further, Patent Literature 2 discloses an area monitoring system that detects an intruder by scanning a laser in a monitor target area and detecting reflection light.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Application Laid-open No. H10-105867

PTL 2: Japanese Patent Application Laid-open No. 2017-9315

SUMMARY OF INVENTION Technical Problem

In the object detection system using light as described in Patent Literature 1 and 2, further improvement in detection accuracy may be required depending on the application.

The present invention has been made in view of the problems described above and intends to provide an object detection system with improved detection accuracy and an article display shelf provided with the object detection system.

Solution to Problem

According to one example aspect of the present invention, provided is an object detection system including: a ranging device that emits light so as to pass through a detection region and receives reflected light in which the ranging device is configured to perform a scan by changing an optical path of emitted light; and a reflection member that is provided in a scan range so as to reflect light passing through the detection region toward the ranging device.

Advantageous Effects of Invention

According to the present invention, an object detection system with improved detection accuracy and an article display shelf provided with the object detection system can be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating a general configuration of an object detection system according to a first example embodiment.

FIG. 2 is a graph illustrating an intensity distribution of reflection light at the time of object detection by the object detection system according to the first example embodiment.

FIG. 3 is a schematic diagram illustrating a configuration example of a reflection surface of a reflection member according to the first example embodiment.

FIG. 4 is a schematic perspective view illustrating a structure of a ranging device according to a first configuration example.

FIG. 5 is a schematic front view illustrating the structure of the ranging device according to the first configuration example.

FIG. 6 is a schematic top view illustrating the structure of the ranging device according to the first configuration example.

FIG. 7 is an optical path diagram in the case where a reflection surface is provided at the vertex of the parabola.

FIG. 8 is an optical path diagram in the case where the reflection surface is not provided at the vertex of the parabola.

FIG. 9 is an optical path diagram in the case where the reflection surface is not provided at the vertex of the parabola.

FIG. 10 is a schematic top view illustrating the structure of the ranging device according to a second configuration example.

FIG. 11 is a schematic top view illustrating the structure of the ranging device according to a third configuration example.

FIG. 12 is a schematic perspective view illustrating the structure of the ranging device according to a fourth configuration example.

FIG. 13 is a schematic top view illustrating the structure of the ranging device according to the fourth configuration example.

FIG. 14 is a sectional view of a logarithmic spiral reflection mirror of the ranging device according to the fourth configuration example.

FIG. 15 is a diagram illustrating a reflection of light at the reflection surface forming a logarithmic spiral.

FIG. 16 is a schematic front view illustrating the structure of the ranging device according to a fifth configuration example.

FIG. 17 is a schematic top view illustrating the structure of the ranging device according to the fifth configuration example.

FIG. 18 is a schematic perspective view illustrating the structure of the ranging device according to a sixth configuration example.

FIG. 19 is a schematic top view illustrating the structure of the ranging device according to the sixth configuration example.

FIG. 20 is a schematic perspective view illustrating a structure of an article display shelf according to a second example embodiment.

FIG. 21 is a schematic side view illustrating the structure of an article display shelf according to the second example embodiment.

FIG. 22 is a schematic front view illustrating a structure of an article display shelf according to a third example embodiment.

FIG. 23 is a schematic side view illustrating a structure of an article display shelf according to a fourth example embodiment.

FIG. 24 is a schematic perspective view illustrating a structure of an article display shelf according to a fifth example embodiment.

FIG. 25 is a block diagram illustrating a general configuration of an object detection system according to a sixth example embodiment.

DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same components or corresponding components are labeled with same references, and the description thereof may be omitted or simplified.

First Example Embodiment

FIG. 1 is a schematic diagram illustrating a general configuration of an object detection system according to the first example embodiment. The object detection system includes a ranging device 100, a control device 200, and a reflection member 800. The object detection system is a system that detects an object 10 in a detection region 850 between the ranging device 100 and the reflection member 800.

The ranging device 100 is a device such as a Light Detection and Ranging (LiDAR) device, for example. The ranging device 100 can acquire a distribution of the distance from the ranging device 100 by emitting a light so as to scan within a predetermined range and detecting a reflection light from an object within the scan range. Although FIG. 1 illustrates a single ranging device 100, the object detection system may be configured to include a plurality of ranging devices 100. Note that, in the present specification, light is not limited to visible light but may include invisible light that cannot be viewed by a naked eye, such as an infrared ray, an ultraviolet ray, or the like.

The control device 200 is a computer, for example. The control device 200 has an interface (I/F) 210, a control unit 220, a signal processing unit 230, and a storage unit 240. The interface 210 is a device that connects the control device 200 and the ranging device 100 so as to be able to communicate with each other in a wired or wireless manner. Thereby, the control device 200 and the ranging device 100 are communicably connected to each other. The interface 210 may be a communication device based on the specification such as Ethernet (registered trademark), for example. The interface 210 may include a repeater device such as a switching hub. When the object detection system has a plurality of ranging devices 100, the control device 200 can control the plurality of ranging devices 100 by relaying via a switching hub or the like.

The control unit 220 controls the operation of the ranging device 100. The signal processing unit 230 acquires distance information on an object 10 inside a detection region 850 by processing a signal acquired from the ranging device 100. The function of the control unit 220 and the signal processing unit 230 may be implemented when a processor such as a central processing unit (CPU) or the like provided in the control device 200 reads a program from a storage device and executes the program, for example. The storage unit 240 is a storage device that stores data acquired by the ranging device 100, a program and data used in the operation of the control device 200, or the like. Accordingly, the control device 200 has a function of controlling the ranging device 100 and a function of analyzing a signal acquired by the ranging device 100.

The reflection member 800 is a member that reflects light emitted from the ranging device 100 toward the ranging device 100. The reflection member 800 is provided within the scan range of the ranging device 100, and reflects the light passing through the detection region 850 toward the ranging device 100.

FIG. 2 is a graph illustrating an intensity distribution of reflection light at the time of object detection by the object detection system according to the present example embodiment. The horizontal axis of FIG. 2 represents a position in the scan direction, and the range indicated by reference numeral 10 represents the range in which the object 10 exists. The vertical axis of FIG. 2 is a signal intensity based on the light received by the ranging device 100.

A solid line to which the label (a) is attached is a signal intensity distribution in the case where a reflection member 800 having a reflectance greater than that of the object 10 is provided. A broken line to which the label (b) is attached is a signal intensity distribution in the case where a reflection member 800 having a reflectance similar to that of the object 10 and smaller than that of the label (a) is provided. The one-dot chain line to which the label (c) is attached is a signal intensity distribution when the reflection member 800 is not provided. Note that, in the case where the reflectance shows wavelength dependence, the “reflectance” here means the reflectance at the wavelength of light emitted from the ranging device 100 and detected, that is, light used for sensing. The same applies to the absorptance. For example, when the laser beam emitted from the ranging device 100 is an infrared ray having a wavelength of 905 nm, the above-described “reflectance” is assumed to be a reflectance with respect to an infrared ray having a wavelength of 905 nm.

As illustrated in FIG. 2, by providing the reflection member 800, the signal intensity due to the reflection light outside the region where the object 10 is provided is increased. This makes it possible to increase the signal intensity particularly in a region where the object 10 is not present, thereby improving the Signal to Noise (S/N) ratio.

The spatial resolution, distance accuracy, or the like at the time of performing distance measurement by scanning light using the ranging device 100 such as a LiDAR device or the like depend not only on the distance between measurement points and the performance of components used in the ranging device 100, but also on the S/N ratio of a signal to be received. In the object detection system of the present example embodiment, the signal intensity can be increased in a region where the object 10 is not present, and the spatial resolution, distance accuracy, or the like can be improved.

In the detection of the object 10, since it is necessary to distinguish between the region where the object 10 is present and the region where the object 10 is absent, not only the region where the object 10 is present but also the spatial resolution, distance accuracy, or the like of the region where the object 10 is absent greatly contribute to the detection accuracy. Therefore, according to the present example embodiment, the object detection system having improved detection accuracy is provided by providing the reflection member 800.

As it can be understood from the comparison between the solid line with the label (a) and the broken line with the label (b), it is desirable that the intensity of the reflection light be increased as the reflectance of the reflection member 800 is increased, and for example, it is desirable that the reflectance of the reflection member is greater than that of the object 10.

A specific configuration of the reflection member 800 will be described. In order to increase the intensity of the reflection light, the reflection member 800 preferably includes at least a part of a member that reflects light in a mode other than diffused reflection so as to reflect the light of strong intensity toward the ranging device 100. In other words, of the reflected light from the reflection member 800, it is desirable that the intensity of the reflection light from the reflection member 800 toward the ranging device 100 is stronger than that of the reflected light from the reflection member 800 toward the direction other than the ranging device 100. Such member may be, for example, a retroreflection material or a specular reflection material.

The retroreflection material is a reflection material configured such that the direction of reflection light is substantially opposite to the direction of emission. Specific examples of the reflection element used for the retroreflection material include a corner cube, a spherical lens or the like. Also, the form of the retroreflection material is not particularly limited, and a reflector in which corner cubes, spherical lenses, or the like are arranged on a substrate, a reflection film in which corner cubes, spherical lenses, or the like are arranged on a film, a reflection coating including spherical lenses, or the like can be used.

The specular reflection material reflects light in accordance with the law of reflection such that the angle of emission and the angle of reflection with respect to the normal of the reflection surface are equal. The specular reflection material may be, for example, a metal subjected to mirror polishing, a film formed with a metal thin film, a metallic luster coating, or the like.

The retroreflection material has a function of returning the light toward the direction of emission regardless of the direction of the emission light. Therefore, when a retroreflection material is used for the reflection member 800, there is an advantage that the installation direction of the reflection member 800 is not limited. On the other hand, in the case where the specular reflection material is used for the reflection member 800, there is a limitation that the reflection surface of the reflection member 800 must be arranged perpendicular to the direction of emission in order to return light to the direction of emission, but there is an advantage that the reflectance can be easily increased.

Next, a specific example of a configuration of a reflection surface of a reflection member 800 will be described. FIG. 3 is a schematic diagram illustrating a configuration example of the reflection surface 800 a of the reflection member 800.

FIG. 3 is a diagram of the reflection surface 800 a of the reflection member 800 viewed from the light emission side. The reflection surface 800 a includes a first part R1 and a second part R2. The reflectance of the light of the second part R2 is less than that of the light of the first part R1. In other words, the light absorptance of the second part R2 is greater than that of the first part R1.

The light emitted from the ranging device 100 and the light reflected by the reflection member 800 and returning to the ranging device and detected by the ranging device 100 pass through the same optical path in the opposite direction. Therefore, structures outside the optical path, such as outside the scan range in the reflection surface 800 a, ideally do not affect detection accuracy. However, the light flux emitted from the ranging device 100 has a certain width, and light may leak out of the scan range. Further, since the reflection light by the reflection member 800 may include an element of diffused reflection in addition to the specular reflection, the light diffusely reflected outside the scan range may be incident on the ranging device 100. Thus, in reality, stray light as noise may be generated by reflection outside the assumed optical path. Such stray light may affect the detection accuracy. The reflection surface 800 a of FIG. 3 includes a second part R2 having low light reflectance. By arranging the second part R2 at an appropriate position, it is possible to attenuate an element of the light reflected by the reflection surface 800 a which may affect the detection accuracy, and the detection accuracy can be improved.

It is desirable that the first part R1 is within a range where light is incident when the ranging device 100 scans the emission light, and the second part R2 is within a range where light is not incident when the ranging device 100 scans the emission light. When the ranging device 100 scans the emission light, the light reflected at the second part R2 on the reflection surface 800 a becomes stray light. When such light is incident on the ranging device 100, it becomes noise, so it is desirable to lower the reflectance of light from outside the scan range.

As illustrated in FIG. 3, it is also desirable that the second part R2 is arranged surrounding the first part R1. This is because it is desirable to provide the second part R2 having low reflectance of light around the first part R1 since the reflection causing stray light is likely to occur around the scan range.

Next, a specific method of forming the first part R1 and the second part R2 will be described. When the reflection member 800 is provided with a reflection material such as a retroreflection material or a specular reflection material, these reflection materials are arranged in the first part R1 and these reflection materials are not arranged in the second part R2, thereby the reflectance of the second part R2 can be made less than that of the light of the first part R1.

When the entire reflection member 800 is made of a base member such as an aluminum alloy, the first part R1 and the second part R2 are made of the same base member. In this case, the surface of the base member of the second part R2 has a surface treated to reduce reflectance so that the reflectance of the second part R2 can be made lower than that of the first part.

As a specific example of a treatment for reducing the reflectance, a treatment for covering the surface of the second part R2 with a light absorbing material by applying a coating material having light absorbing properties, sticking a light absorbing film or the like, forming a light absorbing thin film (for example, deposition or plating) or the like can be applied. In addition, the surfaces of the first part R1 and the second part R2 may be covered with different materials using the above-described method. By using such a manufacturing method, the reflection member 800 can be manufactured more easily than when the first part R1 and the second part R2 are made of different base member.

As another example of the treatment of covering with the light absorbing material, the surface of the reflection surface 800 a may be oxidized by anodic oxidation to form the light absorbing material. Alternatively, the surface of the second part R2 may be polished with a coarser abrasive material than the first part R1, and the surface roughness of the second part R2 may be made greater than that of the first part R1 to reduce the reflectance. According to these manufacturing methods, the parabolic reflection mirror 800 can be easily manufactured without separately supplying the light absorbing material.

However, different base members may be combined to form the first part R1 and the second part R2. In this case, a material having less reflectance than that of the base member of the first part is used as the base member of the second part R2. For example, by using a metal such as an aluminum alloy as the base member of the first part R1 and a resin or the like as the base member of the second part R2, the reflection member 800 can be made lightweight.

The configuration of the object detection system described above is an example, and the object detection system may further include a device that collectively controls the ranging device 100 and the control device 200. Further, the object detection system may be an integrated device in which the function of the control device 200 is incorporated in the ranging device 100.

Although the configuration of the ranging device 100 that may be used in the object detection system is not particularly limited, some configuration examples of the ranging device 100 will be described.

[First Configuration Example of Ranging Device]

FIG. 4 is a schematic perspective view illustrating the structure of the ranging device 100 according to the first configuration example. FIG. 5 illustrates the structure of the ranging device 100 viewed from the front. FIG. 6 illustrates the structure of the ranging device 100 viewed from the top. The structure of the ranging device 100 will be described with reference to these figures. Note that, the x-axis, the y-axis, and the z-axis illustrated in each drawing are solely provided for helping the description and are not intended to limit the arrangement direction of the ranging device 100.

As illustrated in FIG. 4, the ranging device 100 includes a base body 110, a lid body 120, a sensor unit 130, a parabolic reflection mirror 140, a position adjustment mechanism 150, and a plane reflection mirror 160, and a mounting portion 170.

The base body 110 is a member shaped in a rectangular plate and functions as a part of the housing of the ranging device 100. The base body 110 has a function of fixing the sensor unit 130, the parabolic reflection mirror 140, the plane reflection mirror 160 or the like at a predetermined position.

The lid body 120 is a lid covering the base body 110, and functions as a part of the housing of the ranging device 100. In the internal space of the housing surrounded by the base body 110 and the lid body 120, the parabolic reflection mirror 140, the position adjustment mechanism 150, and the plane reflection mirror 160 are arranged.

The sensor unit 130 is a two-dimensional LiDAR device. As illustrated in FIG. 5, the sensor unit 130 can perform rotational scan about the rotation axis u. The sensor unit 130 includes a laser device for emitting laser light, and a photoelectric conversion element for receiving the reflection light reflected by the object 10 and converting it into an electric signal. As illustrated in FIG. 4, the sensor unit 130 is arranged in a notch formed below the base body 110 and the lid body 120. The light emitted from the sensor unit 130 is incident on the reflection surface 140 a of the parabolic reflection mirror 140.

As an example of a distance detection scheme performed by the sensor unit 130, a TOF (Time Of Flight) scheme may be used. The TOF scheme is a method for measuring a distance by measuring a period from emission of a light to reception of a reflected light.

Note that, the laser light emitted from the sensor unit 130 may be visible light but may be invisible light such as an infrared ray. In a use of detection of an article being put in or taken out from an article display shelf described later or the like, it is desirable that the emission light be invisible light so as not to give discomfort to a user. The laser light may be an infrared ray having a wavelength of around 905 nm, for example.

The parabolic reflection mirror 140 is a reflection mirror having a reflection surface 140 a. The reflection surface 140 a forms a parabola with a point on the rotation axis u as a focal point in a section (xy plane in FIG. 5) perpendicular to the rotation axis u. In other words, the sensor unit 130 is arranged near the focal point of the parabola formed by the reflection surface 140 a, and the rotation axis u is arranged at a position passing through the focal point of the parabola formed by the reflection surface 140 a. The rotation axis u is parallel to the z-axis in FIG. 5. The equation of the parabola is expressed by the following equation (1) when the coordinate of the vertex of the parabola is P(0, 0) and the coordinate of the focal point is F(a, 0).

[Math. 1]

y ²=4ax  (1)

Due to the mathematical nature of the parabola, when light emitted from the sensor unit 130 is reflected by the reflection surface 140 a, the direction of emission of the reflection light is parallel to the axis of the parabola regardless of the angle of the emission light. That is, as illustrated in FIG. 5, in the optical path L1 and the optical path L2 having different emission angles from the sensor unit 130, reflected light by the reflection surface 140 a is parallel to each other. In this manner, by arranging the sensor unit 130 at the focal point of the reflection surface 140 a, parallel scan in which the optical path is moved in parallel in the y-axis direction in accordance with the rotation of the emission light can be performed.

The material of the parabolic reflection mirror 140 may be, for example, an aluminum alloy mainly composed of aluminum. In this case, the reflection surface 140 a may be formed, for example, by smoothing the surface of an aluminum alloy by mirror polishing or plating. Noted that, other parabolic reflection mirrors described later may be formed of the same material and method.

The plane reflection mirror 160 is a reflection mirror having a reflection surface 160 a at least partially forming a plane. The reflection surface 160 a is provided on the optical path of the reflection light on the reflection surface 140 a. As illustrated in FIG. 5 and FIG. 6, the plane reflection mirror 160 changes a direction of the light reflected by the reflection surface 140 a to a direction different from that in the xy plane. More specifically, the light reflected by the plane reflection mirror 160 is almost in the z-axis direction, that is, in a direction almost parallel to the rotation axis u. The light reflected by the plane reflection mirror 160 is emitted to the outside of the ranging device. Thus, the direction of the light emitted from the ranging device 100 is not limited to the direction parallel to the axis of the reflection surface 140 a.

The material of the plane reflection mirror 160 may also be, for example, an aluminum alloy mainly composed of aluminum, as the parabolic reflection mirror 140. In this case, the reflection surface 160 a of the plane reflection mirror 160 may be formed by the same smoothing as the reflection surface 140 a, or may be formed by sticking a plate of an aluminum alloy having a specular gloss to a base member. Noted that, other plane reflection mirrors described later may be formed of the same material and method.

Here, the lid body 120 is configured so as not to absorb, reflect, or the like reflection light from the plane reflection mirror 160. Specifically, for example, a region of the lid body 120 through which reflected light from the plane reflection mirror 160 passes may be formed of a material having transparency. Example of a material having transparency includes acrylic resins. Alternatively, a window may be provided in the lid body 120 so as to form a cavity in a region through which reflected light from the plane reflection mirror 160 passes.

The mounting portion 170 is a part for mounting and fixing the ranging device 100 to an article display shelf or the like. By being fixed by the mounting portion 170, the ranging device 100 can be mounted in any direction. The position adjustment mechanism 150 is a mechanism for finely adjusting the position of the plane reflection mirror 160 when the ranging device 100 is mounted to an article display shelf or the like. Note that, instead of the position adjustment mechanism 150, a drive mechanism for moving the plane reflection mirror 160 may be provided.

The optical paths L1 and L2 illustrated in FIG. 5 and FIG. 6 illustrate optical paths when light is emitted from the sensor unit 130 to the outside. On the other hand, the light reflected by the object 10 and incident on the ranging device 100 passes in the reverse direction along almost the same path as the optical paths L1 and L2 and is received by the sensor unit 130.

The ranging device 100 of the present configuration example has a structure that is thick in the axial direction of the parabolic reflection mirror 140 due to the thickness of the parabolic reflection mirror 140, restrictions on the arrangement position of the sensor unit 130, or the like. On the other hand, the ranging device 100 of the present configuration example includes the plane reflection mirror 160 for reflecting the light reflected by the parabolic reflection mirror 140. The plane reflection mirror 160 can change a direction of the emission light from the ranging device 100 to a direction different from the direction of the axis of the parabola formed by the parabolic reflection mirror. Therefore, in the ranging device 100 of the present configuration example, since the light emission direction can be made different from the axial direction of the parabolic reflection mirror 140, the thickness in the light emission direction can be reduced. Thus, the ranging device 100 of the present configuration example can be easily installed in a narrow place such as between article display shelves. Therefore, according to the present configuration example, the ranging device 100 is provided in which the degree of freedom of the installation location is improved.

In the ranging device 100 of the present configuration example, the reflection surface 140 a of the parabolic reflection mirror 140 is provided so as to exclude the vertex of the parabola. The reason for this configuration will be described with reference to FIGS. 7 to 9.

FIG. 7 is an optical path diagram in the case where the reflection surface 140 b is provided at the vertex P of the parabola. For simplicity of explanation, the sensor unit 130 is simply illustrated as a point light source arranged at the focal point F of the reflection surface 140 b. If the light emitted from the focal point F is not parallel to the axis of the parabola (if not oriented to vertex P), the reflection light does not pass through the focal point F. However, if the light emitted from the focal point F is parallel to the axis of the parabola (direction towards vertex P) and is reflected at the vertex P, the reflection light passes through the focal point F. Therefore, the light emitted from the sensor unit 130 is re-incident on the sensor unit 130. In this case, when the sensor unit 130 receives reflection light different from the reflection light from the object 10, noise may be generated for the measured signal. As described above, when the reflection surface 140 b is provided at the vertex P of the parabola, the detection accuracy may be lowered, and sufficient detection accuracy may not be secured.

In contrast, in the ranging device 100 of the present configuration example, as illustrated in FIG. 8, the reflection surface 140 a is provided so as to exclude the vertex P of the parabola. Therefore, even if the light emitted from the focal point F is parallel to the axis of the parabola, it is not reflected. Therefore, since the reflection light does not re-enter the sensor unit 130, the reduction of the detection accuracy can be suppressed. As described above, according to the present configuration example, since the reflection surface 140 a of the parabolic reflection mirror 140 is provided so as to exclude the vertex of the parabola, the ranging device 100 having improved detection accuracy is provided.

Note that, in FIG. 7, the reflection surface 140 a is arranged on one side of the axis of the parabola, but as in the modification illustrated in FIG. 9, the reflection surface 140 c may be arranged on both sides except for the vertex P of the parabola. A specific configuration example corresponding to this modification will be described later.

[Second Configuration Example of Ranging Device]

Next, as a second configuration example, a configuration example of a ranging device capable of translating a plane reflection mirror will be described. The description of components common to the above-described configuration example is omitted or simplified.

FIG. 10 is a schematic diagram illustrating a structure of a ranging device 101 of the present configuration example as viewed from the top. The ranging device 101 of the present configuration example is provided with a drive mechanism 151 instead of a position adjustment mechanism 150, and a plane reflection mirror 161 instead of a plane reflection mirror 160. The drive mechanism 151 drives the plane reflection mirror 161 to move parallel to the axial direction of the parabolic reflection mirror 140 (x-axis direction in FIG. 10). The drive mechanism 151 includes a drive device such as a motor. The drive mechanism 151 also includes a device for acquiring position information of the plane reflection mirror 161 such as an encoder. These devices are controlled by a control device 200. The position information of the plane reflection mirror 161 acquired by the drive mechanism 151 is supplied to the control device 200.

When the drive mechanism 151 drives the plane reflection mirror 161 to move parallel to the x-axis direction, the reflection light by the plane reflection mirror 161 also moves parallel to the x-axis direction. Thus, the ranging device 101 of the present configuration example is capable of scanning to translate the reflection light by the plane reflection mirror 161 in the x-axis direction. As in the first configuration example, the ranging device 101 of the present configuration example is also capable of scanning to translate the reflection light by the plane reflection mirror 161 in the y-axis direction. Therefore, the ranging device 101 of the present configuration example functions as a three-dimensional sensor device capable of acquiring three-dimensional position information by combining two-dimensional scan in the x-axis direction and the y-axis direction and distance measurement in the z-axis direction, in addition to obtaining the same effect as that of the first configuration example.

[Third Configuration Example of Ranging Device]

Next, as a third configuration example, a configuration example of a ranging device capable of rotating and moving a plane reflection mirror will be described. The description of components common to the first configuration example is omitted or simplified.

FIG. 11 is a schematic diagram illustrating a structure of a ranging device 102 of the present configuration example as viewed from the top. The ranging device 102 of the present configuration example is provided with a drive mechanism 152 instead of a position adjustment mechanism 150, and a plane reflection mirror 162 instead of a plane reflection mirror 160. The drive mechanism 152 drives the plane reflection mirror 162 to rotate about a rotation axis v parallel to the y-axis. The position of the rotation axis v may be a position where the direction of the reflection light from the plane reflection mirror 162 changes according to the rotation, and may be, for example, on a path through which the reflection light from the parabolic reflection mirror 140 passes. The drive mechanism 152 includes a drive device such as a motor. The drive mechanism 152 also includes a device for acquiring angle information of the plane reflection mirror 162 such as an encoder. These devices are controlled by a control device 200. The angle information of the plane reflection mirror 162 acquired by the drive mechanism 152 is supplied to the control device 200.

When the drive mechanism 152 drives the plane reflection mirror 162 and the plane reflection mirror 162 rotates, the direction of the reflection light from the plane reflection mirror 162 also rotates. Thus, the ranging device 102 of the present configuration example can perform a scan to rotate and move the direction of the reflection light from the plane reflection mirror 162. As those described in the first configuration example, the ranging device 102 of the present configuration example is also capable of scanning the plane reflection mirror 162 so as to translate the reflection light in the y-axis direction. Therefore, the ranging device 102 of the present configuration example functions as a three-dimensional sensor device capable of acquiring three-dimensional position information by combining rotational movement on the rotational axis v, parallel movement in the y-axis direction, and distance measurement, in addition to obtaining the same effect as in the first configuration example.

[Fourth Configuration Example of Ranging Device]

Next, as a fourth configuration example, a configuration example of a ranging device further including a logarithmic spiral reflection mirror will be described. The description of components common to the above-described configuration examples is omitted or simplified.

FIG. 12 is a schematic perspective view illustrating a structure of a ranging device 300 according to the fourth configuration example. FIG. 13 is a schematic view illustrating the structure of the ranging device 300 as viewed from the top. The structure of the ranging device 300 will be described with reference to these figures. Note that, in FIG. 12 and FIG. 13, components that are not necessary for the description of an optical path, such as the base body 110, the lid body 120, and the mounting portion 170, may be omitted.

The ranging device 300 includes a sensor unit 130, a parabolic reflection mirror 340, a drive mechanism 351, a logarithmic spiral reflection mirror 361, and plane reflection mirrors 362, 363, 364, and 365. The parabolic reflection mirror 340 has reflection surfaces 340 a and 340 b. The reflection surfaces 340 a and 340 b form parabolas, in a section perpendicular to the rotation axis u (xy plane in FIG. 12), focusing on a point on the rotation axis u. The reflection surfaces 340 a and 340 b are perpendicular to each other in the xz plane as illustrated in FIG. 13.

Light emitted from the sensor unit 130 in the negative direction of the x-axis is reflected in the z-axis direction by the reflection surface 340 a, and then reflected in the positive direction of the x-axis toward the logarithmic spiral reflection mirror 361 by the reflection surface 340 b. By causing the reflection surface 340 a and 340 b to reflect twice to shift the optical path in the z direction, the reflection light from the parabolic reflection mirror 340 can be prevented from being inhibited by the sensor unit 130. Further, since the reflection light does not re-enter the sensor unit 130, the detection accuracy can be improved for the same reason as that described with reference to FIGS. 7 to 9.

The logarithmic spiral reflection mirror 361 has a columnar shape, and has a reflection surface 361 a forming a logarithmic spiral on the side faces thereof. The light emitted from the sensor unit 130 is reflected by the reflection surface 361 a. The logarithmic spiral reflection mirror 361 is rotatable about a rotation axis w by the drive mechanism 351. At this time, the light reflected by the reflection surface 361 a moves in parallel according to the angle of the logarithmic spiral reflection mirror 361.

With reference to FIG. 14 and FIG. 15, a more specific structure of the logarithmic spiral reflection mirror 361 will be described. FIG. 14 is a sectional view of the logarithmic spiral reflection mirror 361 according to the present configuration example in a plane perpendicular to the rotation axis w. The reflection surface 361 a that is the side face of the logarithmic spiral reflection mirror 361 forms a closed curve in which four logarithmic spirals are continuously connected in a cross section perpendicular to the rotation axis w. With a closed curve in which logarithmic spirals are continuously connected as described above, a configuration in which the entire reflection surface 361 a that light emitted from the sensor unit 130 may enter forms a logarithmic spiral in a cross section perpendicular to the rotation axis w is realized. Accordingly, even when light enters any of the surfaces of the logarithmic spiral reflection mirror 361, it is possible to utilize reflected light for a scan. Note that, a logarithmic spiral may be referred to as an equiangular spiral or a Bernoulli's spiral.

FIG. 15 is a diagram illustrating reflection of light by a reflection surface forming a logarithmic spiral. The logarithmic spiral Sp is expressed by a polar equation of the following Equation (2):

[Math. 2]

r=a·exp(θ·cot b)  (2)

where r denotes the radial coordinate in the polar coordinate, θ denotes the angular coordinate in the polar coordinate, a denotes the value of r when the value of θ is zero, and b denotes the angle of a line passing through the center of the logarithmic spiral relative to a tangent line of the logarithmic spiral.

Herein, the relationship between the incident light I11 and I21 from the outside of the logarithmic spiral Sp toward the origin O of the polar equation of Equation (2) and the reflected light I12 and I22 thereof is considered. The tangent line and the normal line at a point at which the incident light I11 is reflected by the logarithmic spiral Sp are defined as t1 and S1, respectively, and the tangent line and the normal line at a point at which the incident light I21 is reflected by the logarithmic spiral Sp are defined as t2 and S2, respectively. It is assumed that the incident light I11 is reflected at a point of the radial coordinate r1 on the logarithmic spiral Sp, and the incident light I21 is reflected at a point of the radial coordinate r2 on the logarithmic spiral Sp (where r1≠r2). In this example, due to a nature of the logarithmic spiral Sp, both of the angle of the incident light I11 relative to the tangent line t1 and the angle of the incident light I21 relative to the tangent line t2 are b. Therefore, the incident angle φ of the incident light I11 relative to the normal line S1 and the incident angle φ of the incident light I21 relative to the normal line S2 are the same angle. Also, the reflection angle φ of the reflected light I12 relative to the normal line S1 and the reflection angle φ of the reflected light I22 relative to the normal line S2 are the same angle. When φ and b are angles expressed in the circular measure, the relationship between φ and b is as expressed by the following Equation (3).

$\begin{matrix} \left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack & \; \\ {\phi = {\frac{\pi}{2} - b}} & (3) \end{matrix}$

From the above discussion, it is found that the incident light I11 from the outside of the logarithmic spiral Sp toward the origin O is reflected at the same reflection angle φ even when reflected at any point on the logarithmic spiral Sp. Thus, when the logarithmic spiral Sp is rotated on the origin O, the point at which the incident light I11 to the logarithmic spiral Sp is reflected changes, but the direction in which the reflected light I12 is reflected does not change, and therefore the reflected light I12 moves in parallel.

In the logarithmic spiral reflection mirror 361 of the present configuration example, to utilize the above nature, at least a part of a reflection surface forms a logarithmic spiral in which the rotation axis w matches the origin O in a cross section perpendicular to the rotation axis w. Accordingly, rotation of the logarithmic spiral reflection mirror 361 on the rotation axis w enables a scan so that the light reflected by the reflection surface 361 a moves in parallel.

Returning again to FIG. 13, the parallel scan by the reflection light by the logarithmic spiral reflection mirror 361 will be described. The light reflected by the logarithmic spiral reflection mirror 361 is made incident and reflected on either the plane reflection mirror 362 or the plane reflection mirror 364 according to the angle of the logarithmic spiral reflection mirror 361. The light reflected by the plane reflection mirror 362 is reflected by the plane reflection mirror 363 and emitted to the outside of the ranging device 300. The light emission direction at this time is a positive direction of the z-axis. The light reflected by the plane reflection mirror 364 is reflected by the plane reflection mirror 365 and emitted to the outside of the ranging device 300. The light emission direction at this time is a negative direction of the z-axis.

When the logarithmic spiral reflection mirror 361 rotates clockwise as illustrated in FIG. 13, the light emitted from the ranging device 300 moves in parallel from the optical path L5 toward the optical path L6. When the logarithmic spiral reflection mirror 361 further rotates while the emission light is in the optical path L6, the emission light changes discontinuously from the optical path L6 to the optical path L7. Thereafter, the emission light moves in parallel from the optical path L7 toward the optical path L8, and changes discontinuously from the optical path L8 to the optical path L5. As described above, the ranging device 300 of the present configuration example can alternately scan the positive direction and the negative direction of the z-axis.

Thus, ranging device 300 of the present configuration example is capable of scanning to translate the emission light in the x-axis direction. As in the case of the first configuration example, the ranging device 300 of the present configuration example is also capable of scanning to move the emission light in parallel in the y-axis direction. Therefore, the ranging device 300 of the present configuration example functions as a three-dimensional sensor device capable of acquiring three-dimensional position information by combining two-dimensional scan in the x-axis direction and the y-axis direction and distance measurement in the z-axis direction, in addition to obtaining the same effect as that of the first configuration example. Further, since the ranging device 300 of the present configuration example can alternately scan the positive direction and the negative direction of the z-axis, distance measurement in two different directions can be performed by one ranging device 300.

[Fifth Configuration Example of Ranging Device]

Next, as a fifth configuration example, a configuration example of a ranging device including two optical systems will be described. The description of components common to the above-described configuration examples is omitted or simplified.

FIG. 16 is a schematic view illustrating a structure of a ranging device 400 according to a fifth configuration example as viewed from the front. FIG. 17 is a schematic view illustrating the structure of the ranging device 400 as viewed from the top. The structure of the ranging device 400 will be described with reference to these figures.

The ranging device 400 includes a first optical system 401 and a second optical system 402. The first optical system 401 includes a sensor unit 130, a parabolic reflection mirror 140, and a plane reflection mirror 160. Since the first optical system 401 is the same as the ranging device 100 of the first configuration example, the description thereof is omitted. Note that, the top view of the first optical system 401 is the same as that of FIG. 6.

The second optical system 402 includes a parabolic reflection mirror 440 and a plane reflection mirror 460. The parabolic reflection mirror 440 has reflection surface 440 a. The reflection surface 440 a forms a parabola with a point on the rotation axis u as a focal point in a section perpendicular to the rotation axis u (xy plane in FIG. 16). The parabolic reflection mirror 440 has a line-symmetric structure with the parabolic reflection mirror 140. The plane reflection mirror 460 has a line-symmetric structure with the plane reflection mirror 160. The parabolic reflection mirror 140 and the parabolic reflection mirror 440 are arranged at positions symmetrical to the axis of the parabola. The plane reflection mirror 160 and the plane reflection mirror 460 are arranged at positions symmetrical to the axis of the parabola. Note that, the structure of a housing for storing the components of the second optical system 402 may be, for example, a housing illustrated in FIG. 4 of the first example embodiment reversed in the y direction.

When light is emitted from the sensor unit 130 in the lower left direction in the figure, it is incident on the reflection surface 440 a. The light reflected by the reflection surface 440 a becomes parallel to the axis of the parabola like the optical paths L9 and L10. The light reflected by the reflection surface 440 a, as illustrated in FIG. 17, is emitted to the outside of the second optical system 402.

The reflection surface 140 a of the parabolic reflection mirror 140 and the reflection surface 440 a of the parabolic reflection mirror 440 are provided so as to exclude the vertex of the parabola. This configuration corresponds to the optical path diagram illustrated in FIG. 9. Thus, as described with reference to FIGS. 7 to 9, since the reflection light at the vertex of the parabola is not re-incident on the sensor unit 130, the reduction of the detection accuracy can be suppressed. Therefore, in the present configuration example as well as in the first configuration example, it is possible to provide the ranging device 400 with improved detection accuracy. Further, in the present configuration example, the scan range of the emission light can be widened by using two optical systems.

[Sixth Configuration Example of Ranging Device]

Next, as a sixth configuration example, a configuration example of a ranging device including a logarithmic spiral reflection mirror and two parabolic reflection mirrors will be described. The description of components common to the above-described configuration examples is omitted or simplified.

FIG. 18 is a schematic diagram illustrating a structure of a ranging device 301 according to a sixth configuration example as viewed from an angle. FIG. 19 is a schematic view illustrating the structure of the ranging device 301 as viewed from the top. The ranging device 301 of the present configuration example is a ranging device that the parabolic reflection mirror 340 of the ranging device 300 of the fourth configuration example is replaced with the parabolic reflection mirror 140 and parabolic reflection mirror 440 of the fifth configuration example. In the present configuration example, the same effects as in the fourth configuration example can be obtained. In the present configuration example, the structure of the parabolic reflection mirror is simplified as compared with the fourth configuration example.

Second Example Embodiment

Next, as a second example embodiment of the present invention, a configuration example of an article display shelf including a ranging device 400 in the fifth configuration example will be described. The description of components common to the above-described example embodiment is omitted or simplified.

FIG. 20 is a schematic perspective view of an article display shelf 500 according to a second example embodiment. FIG. 21 is a schematic side view of the article display shelf 500. The structure of the article display shelf 500 will be described with reference to these figures.

The article display shelf 500 is a shelf for displaying articles 540 and may be, for example, a goods display shelf installed in a commercial facility. The article display shelf 500 includes a shelf 510, two ranging devices 400, and a reflection member 800. The two ranging devices 400 are arranged on the one side (first side) surface of the shelf 510. Also, the reflection member 800 is arranged on the other side (second side) surface of the shelf 510 so that the reflection surface 800 a faces the side of the ranging device 400. The shelf 510 is provided with four display portions 520 divided by display plates 530. In the display portion 520, articles 540 such as goods are displayed. That is, the ranging device 400 and the reflection member 800 face each other with the front surface of the display portion 520 interposed therebetween. The display portion 520 includes an opening portion 570 for taking in and out the article 540. The number of the ranging device 400 and the display portion 520 is not limited to those illustrated in the diagrams, and may be plural or single.

The ranging device 400 includes the first optical system 401 and the second optical system 402 described in the fifth configuration example. Light that passes through the first optical system 401 or the second optical system 402 and emits in the positive direction of the z-axis passes across the front of the opening portion 570 of the display portion 520. As a result, i the front of the opening portion 570 of the display portion 520, a detection region 550 by the ranging device 400 is formed. When the customer 560 takes out the article 540 from the display portion 520 or returns the taken out article 540 to the display portion 520, the article 540 and the hand of the customer 560 pass through the detection region 550. The ranging device 400 detects the article 540 or the hand of the customer 560 passing through the detection region 550 to detect the taking in and out of the article 540. When a plurality of articles 540 may be arranged in the display portion 520, the ranging device 400 may detect the position where the article 540 has been taken in and out or the shape of the article 540 which has been taken in and out to specify the article 540 which has been taken in and out.

The reflection member 800 may be the same as that described in the first example embodiment. In FIG. 20, the reflection member 800 is illustrated as a member different from the shelf 510, but a part of the shelf 510 may function as the reflection member 800. The walls of the commercial facility where the article display shelf 500 is installed may function as the reflection member 800.

The article display shelf 500 of the present example embodiment is provided with the ranging device 400, so that it is possible to detect the taking in and out of the articles 540 on display. This function may be used, for example, for the management of goods and the prevention of theft. Further, as described above, since the ranging device 400 has a small thickness in the light emission direction, it is possible to install it in a narrow space on the side surface of the article display shelf 500. Thus, the size of the whole article display shelf 500 can be reduced.

Further, the article display shelf 500 of the present example embodiment is provided with the reflection member 800, whereby for the same reason as that described in the first example embodiment, the detection accuracy of the object in the detection region 550 by taking in and out the article 540 is improved.

Although it is not essential, as illustrated in FIG. 20, it is desirable that the position of the shelf plate 530 in the y-axis direction is between the first optical system 401 and the second optical system 402. In the ranging device 400 according to the fifth configuration example, an insensitive area is formed between the first optical system 401 and the second optical system 402, but the insensitive area can be substantially narrowed by arranging the shelf plate 530 in the insensitive area.

In other words, the configuration that the shelf plate 530 is arranged in the above-described insensitive area can be described as follows. In FIG. 20, the display portions 520 at the first and third stages from the top are called the first display portion, and the display portions 520 at the second and fourth stages from the top are called the second display portion. The opening portion 570 corresponding to the first display portion is called a first opening portion, and the opening portion 570 corresponding to the second display portion is called a second opening portion. At this time, as illustrated in FIG. 20, the light emitted from the first optical system 401 is arranged so as to cross the front of the first opening portion, and the light emitted from the second optical system 402 is arranged so as to cross the front of the second opening portion. In this case, the first display portion and the second display portion are separated from each other by the shelf plate 530, and the position of the shelf plate 530 corresponds to the insensitive area between the first optical system 401 and the second optical system 402.

Note that, the ranging device 400 of the fifth configuration example has been described as an example of the ranging device installed on the article display shelf 500 of the present example embodiment, the ranging device of other configuration examples may be used.

Third Example Embodiment

Next, as a third example embodiment of the present invention, a configuration example of an article display shelf that the arrangement of the ranging device is changed with respect to the second example embodiment will be described. The description of components common to the above-described embodiments is omitted or simplified.

FIG. 22 is a schematic front view of an article display shelf 501 according to the third example embodiment. The article display shelf 501 of the present example embodiment includes a shelf 511 and two ranging devices 400 a and 400 c, and two reflection members 800 arranged around the shelf 511. In the article display shelf 501 of the present example embodiment, the arrangement of the ranging device is different from that in the second example embodiment. The ranging device 400 a is arranged on the left side surface of the shelf 511. The ranging device 400 c is arranged on the upper surface of the shelf 511. The two reflection members 800 are arranged on the right side surface and the lower surface of the shelf 511. Light emitted from each ranging device 400 passes across the front of the display portion 521 and reflects by reflection members 800 facing each other. As a result, a detection region is formed in front of the opening portion 571 of the display portion 521 by the ranging device 400, and the ranging device 400 can detect the taking in and out of the article 540.

In the article display shelf 501 of the present example embodiment, as in the second example embodiment, by providing the reflection member 800, the detection accuracy of the object in the detection region 550 due to the taking in and out of the article 540 is improved.

Further, since the ranging devices 400 a (first sensor device) emit light in the first direction which is the z-axis direction, and the ranging devices 400 c (second sensor device) emit light in the second direction which is the y-axis direction, the light emission directions are perpendicular to each other. Thus, the position where the customer 560 takes the article 540 in and out can be detected from two directions, and the detection accuracy is further improved.

Fourth Example Embodiment

Next, as a fourth example embodiment of the present invention, a configuration example of an article display shelf which the arrangement of the ranging device is changed with respect to the second example embodiment will be described. The description of components common to the above-described embodiments is omitted or simplified.

FIG. 23 is a schematic side view of an article display shelf 502 according to the fourth example embodiment. In the article display shelf 502 of the present example embodiment, the shape of the shelf 511 and the arrangement of the second optical system 402 are different from those of the second example embodiment. In the shelf 511 of the present example embodiment, the lowermost shelf plate 531 protrudes toward the customer. In order to correspond with this, the second optical system 402 provided at the lowermost stage is provided at an angle θ with respect to the first optical system 401 at the upper stage. Thus, the detection region 551 formed by the second optical system 402 provided in the lowermost stage has an angle θ with respect to the detection region 550 formed by the first optical system 401 in the upper stage. Thus, the detection region can be arranged at a proper position even for shelves having different widths of the shelf boards for each stage. When the second optical system 402 is inclined, by rotating the second optical system 402 around the rotation axis u of the sensor unit 130 in the first optical system 401, the detection region can be inclined while maintaining the optical arrangement capable of parallel scan.

Note that, the range of the angle θ is set to be greater than 160 degrees and less than 180 degrees, for example. Since the first optical system 401 and the second optical system 402 are longitudinally elongated in the x direction, members may interfere with each other when the angle θ becomes 160 degrees or less.

In the article display shelf 502 of the present example embodiment, as in the second example embodiment and the third example embodiment, by providing the reflection member 800, the detection accuracy of the object in the detection regions 550, 551 due to the taking in and out of the article 540 is improved.

Fifth Example Embodiment

Next, as a fifth example embodiment of the present invention, a configuration example of an article display shelf including a ranging device 301 according to the sixth configuration example will be described. The description of components common to the above-described example embodiments is omitted or simplified.

FIG. 24 is a schematic perspective view of an article display shelf 503 according to a fifth example embodiment. The article display shelf 503 of the present example embodiment includes shelves 510 and 512, two ranging devices 301, and two reflection members 800. The two ranging devices 301 are arranged between the side surfaces of the shelf 510 and the side surfaces of the shelf 512. The two reflection members 800 are arranged on the other side of the shelf 510 and on the other side of the shelf 512 so that the reflection surface 800 a faces the ranging device 301. Since the ranging device 301 according to the sixth configuration example can emit light in two directions to form a detection region, the ranging device 301 can detect both the left and right shelves 510 and 512 for taking in and out of the article 540. As a result, for example, the number of ranging devices can be reduced as compared with the case where the ranging devices 400 of the fifth configuration embodiment are installed. Note that, the ranging device used for the article display shelf 503 of the present example embodiment may be the ranging device 300 of the fourth configuration example.

In the article display shelf 503 of the present embodiment, as in the second example embodiment to the fourth example embodiment, by providing the reflection member 800, the detection accuracy of the object in the detection region 550 due to the taking in and out of the article 540 is improved.

The device described in the above example embodiments can be configured as in the following sixth example embodiment.

Sixth Example Embodiment

FIG. 25 is a block diagram illustrating a general configuration of an object detection system 900 according to a sixth example embodiment. An object detection system 900 includes a ranging device 901 and a reflection member 902. The ranging device 901 emits light so as to pass through a detection region and receives reflected light. The ranging device 901 is configured to perform a scan by changing an optical path of emitted light. The reflection member 902 is provided in a scan range so as to reflect light passing through the detection region toward the ranging device 901.

According to the present example embodiment, an object detection system 900 having improved detection accuracy is provided.

Modified Example Embodiments

Note that all of the example embodiments described above are mere embodied examples in implementing the present invention, and the technical scope of the present invention should not be construed in a limiting sense by these example embodiments. That is, the present invention can be implemented in various forms without departing from the technical concept or the primary feature thereof. For example, examples in which a part of the configuration of one example embodiment is added to another example embodiment, or examples in which a part of the configuration of another example embodiment is replaced are also example embodiments of the present invention.

The whole or part of the example embodiments disclosed above can be described as, but not limited to, the following supplementary notes.

(Supplementary Note 1)

An object detection system comprising: a ranging device that emits light so as to pass through a detection region and receives reflected light, wherein the ranging device is configured to perform a scan by changing an optical path of emitted light; and

a reflection member that is provided in a scan range so as to reflect light passing through the detection region toward the ranging device.

(Supplementary Note 2)

The object detection system according to supplementary note 1, wherein, of reflected light from the reflection member, intensity of reflected light from the reflection member toward the ranging device is stronger than that of reflected light from the reflection member toward a direction other than the ranging device.

(Supplementary Note 3)

The object detection system according to supplementary note 1 or 2, wherein the reflection member includes a retroreflection material.

(Supplementary Note 4)

The object detection system according to any one of supplementary notes 1 to 3, wherein the reflection member includes a specular reflection material.

(Supplementary Note 5)

The object detection system according to any one of supplementary notes 1 to 4, wherein the reflection member includes a first part and a second part having lower reflectance than the first part.

(Supplementary Note 6)

The object detection system according to supplementary note 5,

wherein the first part is, within a range of the scan, a range in which light emitted from the ranging device is incident, and

wherein the second part is, within a range of the scan, a range in which light emitted from the ranging device is not incident.

(Supplementary Note 7)

The object detection system according to supplementary note 5 or 6, wherein the second part is arranged surrounding the first part.

(Supplementary Note 8)

The object detection system according to any one of supplementary notes 5 to 7,

wherein the first part is provided with either a retroreflection material or a specular reflection material, and

wherein the second part is provided with neither a retroreflection material nor a specular reflection material.

(Supplementary Note 9)

The object detection system according to any one of supplementary notes 5 to 8, wherein a base member at the second part has a surface treated to reduce reflectance.

(Supplementary Note 10)

The object detection system according to supplementary note 9, wherein the surface of the base member at the second part is covered with a light absorbing material.

(Supplementary Note 11)

The object detection system according to supplementary note 9, wherein surface roughness of the base material at the second part is greater than that of the base member at the first part.

(Supplementary Note 12)

The object detection system according to any one of supplementary notes 1 to 11, wherein the sensor unit is a Light Detection and Ranging (LiDAR) device that acquires distance information based on light reflected by the object.

(Supplementary Note 13)

An article display shelf comprising:

the sensor device according to any one of supplementary notes 1 to 12; and

a display portion on which an article is displayed.

(Supplementary Note 14)

The article display shelf according to supplementary note 13,

wherein the ranging device is arranged at a first side of the display portion, and

wherein the reflection member is arranged at a second side of the display portion that faces the first side.

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2018-202829, filed on Oct. 29, 2018, the disclosure of which is incorporated herein in its entirety by reference.

REFERENCE SIGNS LIST

-   10 object -   100-102, 300-301, 400, 400 a, 400 c, 901 ranging device -   110 base body -   120 lid body -   130 sensor unit -   140, 340, 440 parabolic reflection mirror -   140 a-140 c, 160 a, 340 a-340 b, 361 a, 440 a, 800 a reflection     surface -   150 position adjustment mechanism -   151-152, 351 drive mechanism -   160-162, 362-365, 460 plane reflection mirror -   170 mounting portion -   200 control device -   210 interface -   220 control unit -   230 signal processing unit -   240 storage unit -   361 logarithmic spiral reflection mirror -   401 first optical system -   402 second optical system -   500-503 article display shelf -   510-512 shelf -   520-521 display portion -   530-531 display plate -   540 article -   550-551, 850 detection region -   560 customer -   570-571 opening portion -   800, 902 reflection member -   900 object detection system -   R1 first part -   R2 second part 

What is claimed is:
 1. An object detection system comprising: a ranging device that emits light so as to pass through a detection region and receives reflected light, wherein the ranging device is configured to perform a scan by changing an optical path of emitted light; and a reflection member that is provided in a scan range so as to reflect light passing through the detection region toward the ranging device.
 2. The object detection system according to claim 1, wherein, of reflected light from the reflection member, intensity of reflected light from the reflection member toward the ranging device is stronger than that of reflected light from the reflection member toward a direction other than the ranging device.
 3. The object detection system according to claim 1, wherein the reflection member includes a retroreflection material.
 4. The object detection system according to claim 1, wherein the reflection member includes a specular reflection material.
 5. The object detection system according to claim 1, wherein the reflection member includes a first part and a second part having lower reflectance than the first part.
 6. The object detection system according to claim 5, wherein the first part is, within a range of the scan, a range in which light emitted from the ranging device is incident, and wherein the second part is, within a range of the scan, a range in which light emitted from the ranging device is not incident.
 7. The object detection system according to claim 5, wherein the second part is arranged surrounding the first part.
 8. The object detection system according to claim 5, wherein the first part is provided with either a retroreflection material or a specular reflection material, and wherein the second part is provided with neither a retroreflection material nor a specular reflection material.
 9. The object detection system according to claim 5, wherein a base member at the second part has a surface treated to reduce reflectance.
 10. The object detection system according to claim 9, wherein the surface of the base member at the second part is covered with a light absorbing material.
 11. The object detection system according to claim 9, wherein surface roughness of the base material at the second part is greater than that of the base member at the first part.
 12. The object detection system according to claim 1, wherein the sensor unit is a Light Detection and Ranging (LiDAR) device that acquires distance information based on light reflected by the object.
 13. An article display shelf comprising: the sensor device according to claim 1; and a display portion on which an article is displayed.
 14. The article display shelf according to claim 13, wherein the ranging device is arranged at a first side of the display portion, and wherein the reflection member is arranged at a second side of the display portion that faces the first side. 